Method for Measuring Multiple Parameters of a Signal Transmitted by a Signal Generator

ABSTRACT

A method is disclosed for measuring one or more parameters of a signal generated by a signal generator. The method employs capturing and analyzing a train of data packets or other forms of signals from a single transmission to obtain measured values for the one or more parameters. The obtained measured values may be used in valuing a calibration of a signal generator or in verifying the already calibrated values of the signal generator. In accordance with a preferred embodiment, the train of data packets contains packets having different properties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to calibration and testing of atransmitter (referred to herein as a data signal generator) and/or areceiver (referred to herein as a data signal receiver) and moreparticularly, to reduction in test time for performing the measurementof one or more parameters or properties of transmitted signalstransmitted by a device under test (DUT) and/or received by a DUT.

2. Related Art

An electronic transmitter and/or receiver forms a basic component inmobile cell phones, wireless personal computers (PCs), and wirelessdevices in general. Typically, a wireless device is tested foracceptable performance before leaving production facilities. Forexample, part of the testing of the wireless device may includemeasuring quality parameters associated with a transmitted signal thatis output by the wireless device and/or reception capabilities of thetransmitted signal by the receiver of the wireless device.

Traditionally, production testing of a transmitter and/or receiverdevice has followed a sequential flow, testing one property of atransmitted or received signal at a time. The measurement capability ofthe testing equipment has in part driven the need for a sequential flowof testing. For example, typically, hundreds of data packet signals orpackets are transmitted at a same transmitter setting or value for aproperty to be measured, e.g. the output power, to obtain an accuratemeasurement of the property due to the response time of the measurementsystem. For example, to obtain accurate results from a power meter, thedevice under test (DUT) or transmitter must send a same data packetsignal or packet repeatedly while the power meter measures the power byaveraging the measurements taken. The result is read back by the testsystem, and a decision is made regarding the next step of testing. Ifthe power meter were to receive a transmission of data packet signalsvarying in output power, as versus receiving a transmission of packetsat a same power level, the power meter would simply average the result,and not obtain a measurement of the output power of each transmissionpacket. Similar scenarios exist for other testing equipment, such asspectrum analyzers and other typical production measurement equipmentfor testing high frequency systems.

However, testing in such a sequential fashion increases the overall testtime. For example, after transmission of a packet train of packets, e.g.several hundred packets, at a given output power, the power meterprovides the output power measurement for the given output power settingof the transmitter. In order to obtain the transmitter's error vectormagnitude (EVM) value for this power setting, another transmission ofseveral hundred packets at the same transmitter power setting is outputto be measured by EVM measuring equipment. After the EVM equipmentobtains a value for the EVM for packets transmitted at the given outputpower setting of the transmitter, spectrum analyzer equipment may beemployed to measure the spectral mask or spectral dissipation outside apredefined bandwidth. Again, several hundred packets are transmitted atthe given power setting of the transmitter to allow the spectrumanalyzer equipment to obtain a reading on the spectral mask for packetstransmitted at the given output power.

An additional issue contributing to increased test time for testingtransmission equipment and/or receiver equipment is that more moderntransmitters and receivers are capable of transmitting and receivingdata packet signals at multiple frequencies or data rates. Thus, theseveral properties to be measured, e.g. output power, EVM, and spectralmask, may need to be measured at multiple frequencies, besides multipleoutput power levels.

In view of the above, improvements are needed in determining measuredvalues for multiple parameters or properties of a transmission ofpackets by a transmitter and/or reception capabilities by a receiver toreceive the transmission of packets in a timely fashion. A need existsto produce the required measured values in a significantly lesser amountof test time than that offered by the traditional testing methods of thepast.

SUMMARY OF THE INVENTION

A method is disclosed for measuring one or more parameters of a signalgenerated by a signal generator. The method employs capturing andanalyzing a train of data packets or other forms of signals from asingle transmission to obtain measured values for the one or moreparameters. The obtained measured values may be used in valuing acalibration of a signal generator or in verifying the already calibratedvalues of the signal generator. In accordance with a preferredembodiment, the train of data packets contains packets having differentproperties.

In one embodiment, a method is provided for measuring one or moreproperties of an output signal generated by a data packet signalgenerator. The method includes generating a plurality of data packetsignals by the data packet signal generator, a portion of the pluralityof data packet signals having at least one property that varies in valueover a calibrated range of the data packet signal generator. The portionof the plurality of data packet signals is received from the data packetsignal generator for analysis. Measuring the value of the at least oneproperty for the received portion of the plurality of data packetsignals produces measured values.

In another embodiment, a method for measuring one or more properties ofan output signal generated by a data packet signal generator isprovided. The method includes generating a plurality of data packetsignals by varying an output power and data rate of the data packetsignals as generated by the data packet signal generator. The pluralityof data packet signals are received for analysis. A portion of thereceived plurality of data packet signals is measured to producemeasured values for at least one property of the data packet signals ofthe portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood in view of the followingdescription when accompanied by the below figures and wherein likereference numerals represent like elements:

FIG. 1 illustrates a chart showing an example embodiment of a pluralityof data packet signals as generated by a data packet signal generatorand received by an analyzing device;

FIG. 2. illustrates a flowchart describing an example of a method formeasuring one or more properties of an output signal generated by a datapacket signal generator;

FIG. 3 illustrates another chart showing an example embodiment of aplurality of data packet signals as generated by a data packet signalgenerator and received by an analyzing device;

FIG. 4 illustrates a flowchart describing an example of a method thatmeasures one or more properties of an output signal generated by a datapacket signal generator.

FIG. 5 illustrates a chart showing an example embodiment of a pluralityof data packet signals as received by a data packet signal receiver;

FIG. 6 illustrates another chart showing an example embodiment of aplurality of data packet signals as received by a data packet signalreceiver;

FIG. 7 illustrates yet another chart showing an example embodiment of aplurality of data packet signals as received by a data packet signalreceiver;

FIG. 8 illustrates a flowchart describing an example of a method todetermine the capability of a data packet signal receiver to receive atmultiple data rates.

DETAILED DESCRIPTION OF THE INVENTION

In the following discussion, for purposes of consistency and simplicityof examples, the generated transmit signal is generally described interms of data packet signals. However, in accordance with the presentlyclaimed invention, the data signals need not necessarily be in the formof packet data. Alternatively, the generated transmit signals could bein other commonly used forms, such as continuous wave (CW) signals,which represent or otherwise correspond to the specific data, controls,parameters or characteristics sought to be measured, controlled,monitored or tested.

Additionally, the following discussion uses EVM as an example of ameasure of signal quality. However, it should be understood that othermeasures of transmission signal quality can also be used in accordancewith the presently claimed invention. For example, one may analyze thequality of a signal where multiple transmitters with different forms ofmodulation produce a combined signal, e.g., in a MIMO (Multiple InputMultiple Output) system, in which case traditional EVM may not be asuseful due to mutual intereference among the signals, but a compositeEVM of some form can be used to represent the transmitter quality.Similarly, when measuring transmit quality for a traditional GSMtransmitter, the quality is generally represented in terms of integratedphase error, rather than EVM.

With the advent of more modern testing equipment, e.g. a vector signalanalyzer (VSA) and/or a vector signal generator (VSG), an alternative tothe traditional sequential testing and measurement of the properties ofa transmission by a data packet signal generator and the receptioncapabilities of a data packet signal receiver may be provided with animprovement in test time reduction. With the use of more modern testingequipment, e.g. the VSA, a testing process or methods may be employedwherein multiple properties, e.g. output power, EVM, and spectral mask,may be measured for individual packets of a single transmission orpacket train. The following is organized with FIGS. 1-4 pertaining toimprovement in test time for testing a data packet signal generator andFIGS. 5-8 pertaining to improvement in test time for testing a datapacket signal receiver.

FIG. 1 illustrates a chart 100 showing an example embodiment of aplurality of data packet signals 110 as generated by a data packetsignal generator and received by an analyzing device. Herein, datapacket signals are also referred to as just packets or data packets. Thechart 100 of FIG. 1 shows a plot of packet power level vs. time inaccordance with a measurement method or methods as herein described. Asshown in FIG. 1, a portion 120 of the plurality of data packet signals110 repeats periodically, e.g. data packet 1 (DP1), data packet 2 (DP2),. . . , and data packet 6 (DP6) repeat again beginning at time t7.Although the portion 120 is shown with six data packets, a portion mayhave more than or less than six data packets. The sequence of six datapackets DP1-DP6 is shown starting at time t1 and repeats again beginningat time t7. Packet DP1 begins at times t1 and t7, Packet DP2 begins attimes t2 and t8, . . . , with time t1<time t2<time t3< . . . . Theexample of FIG. 1 also shows the packets DP1-DP6 progressivelyincreasing in output power level, e.g. packet DP1 has power level P1,packet DP2 has power level P2, packet DP3 has power level P3, . . . ,and P1<P2<P3< . . . . Each packet in the plurality of data packetsignals 110 is shown with the same or constant packet width, e.g. thepacket width 130 of packet DP1. Packets with a same width representpackets transmitted at a same datarate, e.g. 54 Mbps. Each of theplurality of data packet signals 110 may have a same data or a randomdata, but in the example of FIG. 1, each are assumed to be a same sizeand transmitted at the same data datarate.

However, embodiments other than the one exemplified in FIG. 1 may beused for the methods herein disclosed. For example, the number of datapackets in the portion 120 need not be six. The output power levelsP1-P6 corresponding to the packets DP1-DP6 need not be increasing, andtwo or more packets of the portion 120 may even have the same powerlevel. The data packet signal generator should vary, though, theproperty or properties to be measured in at least two packets of theportion 120.

The plurality of data packet signals 110 of FIG. 1 are generated by adata packet signal generator or transmitter needing calibration withmeasured values or needing verification of calibration values againstmeasured values. An analyzing device, such as a vector signal analyzer(VSA), may be used to capture the portion 120 of the plurality of datapacket signals 110. For example, the VSA may receive the plurality ofdata packet signals 110 and store the portion 120 in a memory, and laterretrieve the stored received portion 120 from the memory for analysis.The capture of the portion 120 may be done by triggering on a packetproperty, e.g. the power level, of a given packet and accepting packetsuntil a packet with the same property value, e.g. same power level, isdetected. The packet with the same property value signals the beginningof another repeated portion 120. As an example, the VSA may trigger tobegin capturing packets when a packet with power level P2 is detected,e.g. data packet DP2 at time t2. Packets are captured and stored in amemory for later analysis until another packet with power level P2, e.g.data packet DP2 at time t8, is detected. In this way, the VSA maycapture and store for later analysis packets DP2, DP3, DP4, DP5, DP6,and DP1. Alternatively, the VSA may be set to trigger on a packet withpower level P5. In this case, the packets DP5, DP6, DP1, DP2, DP3, andDP4 may be captured and stored as the portion 120.

The VSA may allow some predetermined number of packet trains or portions120 to pass before triggering and collecting a portion 120. Often timesthe transmitter requires time to settle or reach an equilibrium, andthus the VSA may not begin collecting or capturing packets (triggering)until enough time has passed to allow for settling of the transmitter.Alternatively, the VSA may not be set up with a triggering, but may beused in a free running mode wherein the time for collecting packets maybe longer than a packet train or portion 120 to ensure collection ofcomplete packets of a complete packet train. Enough time is allowed topass before collecting packets to ensure settling of the system. Lettingthe system settle before taking the measurement may make more difficultthe detection of the start of a packet train as any packet can triggerthe measurement system. However, knowing the type of packets and thepacket order may simplify the task of identifying a packet at a givenlocation in the order. The capture time should be equal to or longerthan the period of the train of packets to be captured.

As soon as the packet capture is completed for a transmitted portion,e.g. the portion 120, the VSA or measurement system can proceed withcapturing another portion 120 at a next frequency or data rate, whilethe packets captured at the previous frequency or data rate areanalyzed. In this way, testing time may be reduced for testingtransmitters capable of transmitting at multiple data rates orfrequencies.

FIG. 2. illustrates a flowchart describing an example of a method 200for measuring one or more properties of an output signal generated by adata packet signal generator. The example method of FIG. 2 begins atblock 210 by preparing the data packet signal generator to generate aplurality of data packet signals 110. At block 220, a predeterminedfrequency or transmit property (e.g. data rate(s)) is selected for thegeneration of the plurality of data packet signals 110. It is possibleto generate a packet, for example, a section of a continuous wavesignal, having multiple data rates for a transmit property. It is to beunderstood that although the term “data packet” or “packet” has beenused herein, e.g. the packets 510, 520, 530, 540, 550, and 560 in FIG.5, the term “data packet” or “packet” may refer to the sections of acontinuous wave (CW) signal. At block 230, the plurality of data packetsignals 110 is generated at the selected predetermined frequency ortransmit property by the data packet signal generator. A portion 120 ofthe generated plurality of data packet signals 110 has at least oneproperty that varies in value over a calibrated range, e.g. a range withgraduations, of the data packet signal generator. For example, the atleast one property may include packet output power, and may be variedover a range of output power, e.g. from power level P1 through P6 asshown in FIG. 1. The output power levels P1-P6 of the generated portion120 span a calibration, e.g. a set of graduations, of the data packetsignal generator, the calibration either to be assigned values or tohave assigned values verified based on measured values. In oneembodiment, the method maps to the calibrated range the measured values,and extrapolates values for the calibrated range for points of thecalibrated range between the measured values. In another embodiment, themethod verifies values of the calibrated range of the data packet signalgenerator against the measured values of the at least one property. Inyet another embodiment, each data packet signal in the portion 120 has adifferent value for the at least one property (e.g. output power), thedifferent values spanning the calibrated range of the data packet signalgenerator.

At block 240, the portion 120 of the plurality of data packet signals110 is received by the receiving analyzing device, e.g. the VSA. Atblock 250, the VSA measures the value of the at least one property forthe received packets of the portion 120 to produce measured values.

The measured values produced by block 250 may include values formultiple properties. For example, the measured values may include valuesfor the output power, error vector magnitude (EVM), and spectral contentor mask of the packets of the portion 120. With the use of asophisticated measuring device, e.g. a VSA, measurements of multiplepacket properties may be made on the packets of the portion 120. Testingtime may be reduced for production testing of electronic transmitters bymeasuring multiple properties of an individual packet in the capturedportion 120 of the plurality of data packet signals 110.

At block 260 a test is performed to determine whether measurements areneeded at other predetermined transmission frequencies or transmissionproperties. If so, at block 270 another predetermined transmissionfrequency or property is selected for another transmission of datapackets. Processing then flows from block 270 back to block 230 torepeat the blocks of processing for blocks 230, 240, and 250. If atblock 260 additional measurements are not needed, processing ends atblock 280 by making the measured values available to the user or tester.It should be understood that two parallel operations could beimplemented for FIG. 2 such that the measurement operation is done inparallel with the next capture (generate and receive) operation.

FIG. 3 illustrates another chart 300 showing an example embodiment of aplurality of data packet signals 310 as generated by a data packetsignal generator and received by an analyzing device. The chart 300 ofFIG. 3 illustrates a packet train that may be used in a measurementsmethod to verify the performance of a device capable of transmittingmultiple data rates at multiple power levels. In FIG. 3, as compared toFIG. 1, the frequency or data rate is varied as well as the output powerof transmitted packets of a portion 320 of the plurality of data packetsignals 310. The width of a packet, e.g. the width 330 of data packet 11(DP11), represents the data rate of the packet, e.g. 54 Mbps for DP1.Thus, as illustrated in FIG. 3, the width 330 (representing 54 Mbps) ofDP11 is different from the width 340 (representing 24 Mbps) of datapacket 14 (DP14). The time between packets of a transmission of packetsmay also vary depending on the analysis needed. For example, for aspectral mask measurement, a longer capture time or capture window 350may be needed to obtain the desired averaging of the spectral mask. Foroptimal operation, the packet length may depend on the measuredproperty, e.g. for EVM measurement, all packets can be the same lengthindependent of the data rate (EVM is measured over X symbols, and thedata rate uses the same symbol length). For power the same is true, butthe packet length may be different for different power levels.

FIG. 3 exemplifies a typical packet train that may be used to testcompliance of a transmitter to a standard, e.g. the IEEE 802.11gstandard. Power and EVM may be measured for packets generated at 54 Mbps(e.g. DP11), 48 Mbps (e.g. DP12), and 36 Mbps (e.g. DP13). In addition,the portion 320 includes packet DP14 (24 Mbps) that may be measured forpower, EVM, and spectral mask and DP15 (6 Mbps) that may be measured forpower and spectral mask. Packets transmitted at 24 Mbps and 6 Mbps aretypically at the same power level because regulations on spectral masktypically require the power level be kept low enough such that spectraldissipation outside the allowed spectral bandwidth be kept withinregulated limits. Thus power may not be increased further for packetswith transmission rates below 24 Mbps. As shown in FIG. 3, DP11-DP13have corresponding power levels P11-P13, and DP14 and DP15 have the samepower level P14. Thus, the packet train or the portion 320 withconsecutive packets DP11, DP12, DP13, DP14, and DP15 can be used tomeasure all of the above noted packet parameters or properties with asingle transmission and capture of packets transmitted at various datarates.

FIG. 4 illustrates a flowchart describing an example of a method 400that measures one or more properties of an output signal generated by adata packet signal generator. The example method 400 begins at block 410by preparing the data packet signal generator to generate a plurality ofdata packet signals, for example, the plurality of data packet signals310 of FIG. 3. As described for FIG. 3, the portion 320 of the pluralityof data packet signals 310 has data packet signals that differ in bothtransmission data rate and output power from other data packet signalsof the portion 320. It may be that each of the data packet signals ofthe portion 320 are varied in both data rate and output power. At block420, a plurality of data packet signals, e.g. the plurality of datapacket signals 310, is generated by varying an output power and datarate of the data packet signals as generated by the data packet signalgenerator. At block 430, the plurality of data packet signals isreceived for analysis. At block 440, a portion, e.g. the portion 320, ofthe received plurality of data packet signals is measured to producemeasured values for at least one property of the data packet signals ofthe portion.

The measured values produced in block 440 may include values formultiple properties. For example, the measured values may include valuesfor the output power, error vector magnitude (EVM), and spectral contentor mask of the packets of the portion 320. With the use of asophisticated measuring device, e.g. a VSA, measurements of multiplepacket properties may be made on the packets of the portion 320.

At block 450, the processing of method 400 ends by making the measuredvalues available to the user or tester. The measured values may, forexample, be used to verify the values of a calibrated range of the datapacket signal generator.

Similar to the use of a multipacket transmission of packets with varyingpacket properties by a data packet signal generator for analysis, onecan also utilize a multi-packet reception of packets with varying packetproperties by a data packet signal receiver. The use of one multi-packettransmission of packets with varying packet properties may provide for areduction in test time for both the data packet signal generator and thedata packet signal receiver.

In accordance with the discussion in U.S. patent application Ser. No.10/908,946, filed Jun. 1, 2005 (the disclosure of which is incorporatedherein by reference), a multi-packet train or transmitted signalcomprised of packets with varying packet properties can be used to makea timely determination of the sensitivity or performance of a datapacket signal receiver. In accordance with the presently claimedinvention, a transmitted signal or multi-packet train comprised ofvarying packet properties can be used to timely determine the receivecapability of a data packet signal receiver to receive multiple datarates. Additionally, this disclosure further describes the use of asignal with a packet train of packets at multiple power levels totest/adjust (e.g. calibrate) the accuracy of the receive signal strengthindicator (RSSI) of the data packet signal receiver.

Production testing of a receiver typically may require testing time todetermine the sensitivity of the receiver and to ensure the deviceperforms according to specification. Sensitivity and performanceaccording to specification may be measured as a combination of a noisefigure of the analog front end and a performance verification of thedigital signal processing in the modem.

A modem receiver may support multiple data rates to obtain the bestpossible data throughput for the given signal level. An example of thisis the IEEE 802.11g standard wherein most systems (transmitter andreceiver) support 1, 2, 5.5, 6, 9, 11, 12, 18, 24, 36, 48, and 54 Mbpsdata rates. The basic difference in this case is the modulation andcoding used to achieve these data rates. As the receiver will not knowwhat data packet is to be received first, then next, and so forth, thereceiver must have the analog (radio frequency or RF) portion of thereceiver identical for all possibly received packets, so only the modem(digital signal processing (DSP)) portion will differ. Thus, testing ofthe data packet signal receiver may only require checking sensitivity ata single modulation or data rate, and verifying modem operation at theremaining data rates.

In a typical production test, the receiver is typically able to beoperated in a mode wherein the receiver simply receives packets andcounts the good and bad packets. From the count of good and bad packets,the receiver performance (sensitivity and data rate capabilities) may bedetermined.

Traditionally, a predetermined number of packets, e.g. 1000 packets, aretransmitted at a given power level (or at multiple power levels asdescribed in the aforementioned U.S. patent application Ser. No.10/908,946) to test the sensitivity. If the pass limit is 10% packeterror rate (PER), then 900 or more packets must be received to pass thesensitivity test.

Once passing the sensitivity test, it may be assumed that the noisefigure is acceptable, and that the modem operates correctly for thegiven data rate. In the case of a multiple data rate receiver, what isleft is to test the remaining data rates. Traditionally, one would starttransmitting at a new data rate, to verify the correct operation of thereceiver at that data rate. This is not efficient, though, asreconfiguring the system is needed to transmit and receive at a new datarate. To eliminate the time for reconfiguring the transmitter andreceiver system, multiple packet transmit and receive testing may bedone wherein the system is configured to transmit and receive a wavetrain of packets with packets at multiple data rates.

Rather than transmitting a same packet multiple times, the example ofFIG. 5 shows the transmission and reception of a wave train 500 ofpackets comprising one packet of each modulation or data rate to betested. For example, FIG. 5 shows a fundamental waveform in a typicalIEEE 802.11g standard receiver. A 48 Mbps packet is not shown in FIG. 5since a 54 Mbps packet 510 and the 48 Mbps packet (not shown) areidentical for the modem or modulation (orthogonal frequency-divisionmultiplexing (OFDM) for which the data rates, in Mbps, are 54, 48, 35,24, 18, 12, 9 and 6), only differing in coding. Likewise, a 12 Mbpspacket is not shown in FIG. 5 since an 18 Mbps packet 540 and the 12Mbps packet (not shown) are identical for the modem or modulation(OFDM), only differing in coding. Likewise, the same is true for a 11Mbps packet 520 and a 5.5 Mbps packet (with direct-sequence spreadspectrum (DSSS) modulation for which the data rates, in Mbps, are 11,5.5, 2 and 1, and complementary code (CCK) coding) (not shown), a 36Mbps packet 530 and a 24 Mbps packet (OFDM) (not shown), and so forth.In the example of FIG. 5, the transmitted signal or wave train 500 hasall transmitted packets at a substantially same transmission powerlevel.

Since in the example of FIG. 5 all packets of the wave train 500 havethe same power level, if the packets are transmitted at a power levelacceptable for the receiver sensitivity for the 54 Mbps packets, thenall remaining packets should be received without problems if the modemsfor their data rates work correctly, as the lower data rates have asignal-to-noise ratio (SNR) requirement lower than the 54 Mbps.

In the example of FIG. 5, if 1000 of the wave train 500 are transmitted,and thus 1000 of each of the shown packets in the wave train 500, 6000packets are transmitted for reception by the receiver. In this case only54 Mbps packets are expected to fail, and at a sensitivity of 10% packeterror rate (PER) for the 54 Mbps packets, only 100 of the 1000 54 Mbpspackets would be expected to fail. Thus 5,900 of the 6000 transmittedpackets, or 98.33% of the packets would be expected to be receivedcorrectly if the receiver modems are working correctly for the multipledata rates. If a modem does not work correctly for one of the packettypes or data rates, one would easily see this, as an additional 1000packets are likely to be missing in this case. In this manner, the countof the total number of correctly received packets for one transmissionor wave train may be used to determine whether the data packet signalreceiver is operating correctly at all data rates for which the receiveris tested.

In the example of FIG. 5, the shown packets of the packet wave train 500may also have non-critical packets made shorter (e.g., transmitted withless data to make the execution time faster). The non-critical packetsare those not tested at sensitivity level for their associated datarates, and thus it should not matter how long the non-critical packetsare for the data rates tested at other than sensitivity. Accordingly,the 54 Mbps data packets of FIG. 5 may be tested at sensitivity ifdesired, and if so, are critical for use in determining sensitivity ofthe receiver. Ideally, the data packet signal receiver should reportstatistics for the individual data rates. If this were the case, a baddata packet signal receiver could be identified more easily.

In the example of FIG. 6, the individual packets of the wave train 600are scaled in their transmit power level. Each packet of the wave train600 is scaled or transmitted at a power level at the associatedsensitivity for the packet data rate, so the pass level is expected tobe at 90% good packets for a receiver with correctly operating modems.Again, if the modem fails for a given packet type, an additional 900 badpackets can be expected. So a failing modem should still be detectable.For example, in FIG. 6 if 1000 of each of the shown packets aretransmitted at their sensitivity level, then with a 10% fail rate (PER)at each received data rate, one would expect 6*900 or 5400 packetsreceived correctly (90% pass rate). If a modem failed 900 more packetswould not be received correctly, giving a result of 4500 packetsreceived correctly or a 75% pass rate. In this manner, the count of thetotal number of correctly received packets for one transmission or wavetrain 600 may be used to determine whether the data packet signalreceiver is operating correctly at all data rates for which the receiveris tested. However, with regard to the example of FIG. 6, one should becareful in adding or testing too many data packet rates, as a goodreceiver could potentially mask a modem failing one data rate. Forexample, a packet train or waive train of 10 packets, each withdifferent data rates, where all packets but one is received perfectly,could mask the one failing a 100%. For example, if a 1000 wave trains of10 packets in a wave train with different data rates is transmitted andreceived such that 9 data rates are received perfectly (9*1000=9000packets received correctly) and one modem is failing completely (so 1000packets not received), then the result is still 9000 of 10000 packetsreceived correctly, or a 10% fail rate (10% PER). Thus, what appears tobe a good receiver having a pass rate of 90% is actually a failingreceiver, failing completely at a given data rate.

It should be understood that someone skilled in the art can easilyrealize other combinations where some packets are scaled and some arenot. For example, FIG. 7 shows a packet or wave train 700 wherein twopackets 770 and 780, e.g. two data rates, are at power levels differentfrom the rest of the wave train packets 710, 720, 730, 740, 750, and760, the rest of the wave train packets being at a same power level. Forexample, the packets 770 and 780 could be at power levels correspondingto the sensitivity for the associated data packet rates.

It is to be understood that one of common knowledge in the art mayfurther determine combinations of scaled power and multiple data ratepackets to be used in accordance with the methods disclosed in theaforementioned U.S. patent application Ser. No. 10/908,946 to measuresensitivity of a given packet as well as test multiple data rates. Theadvantage of combining these is that only one wave train need be used totest all functionality, thus reducing the overall test time. It shouldbe noted, that it may be difficult to combine varying data rate to testthe sensitivity, as one will have a data rate where all data is likelyto fail, and in this case, one will most likely not test thefunctionality of the modem at the same time, as most packets are alreadyfailing. However, as provided by the example of FIG. 7, multiple datarate packets may be tested on the “pass side” though.

FIG. 8 illustrates a flowchart describing an example of a method todetermine the capability of a data packet signal receiver to receive atmultiple data rates. The flowchart 800 begins at 810 with thetransmission of a wave train some predetermined number of times, forexample the wave train 500 of FIG. 5. At 820 the data packet signalreceiver receives a plurality of data packet signals, wherein at leastfirst and second ones of a portion of the received plurality of datapacket signals have first and second ones respectively of at least tworeceiver-supported data rates. At 830 the total number of correctlyreceived data packet signals is determined from the received portion. At840, the total number of correctly received data packet signals iscompared to a predetermined number. A correct operation of the datapacket signal receiver at the at least two receiver-supported data ratesmay be determined as a result of the comparison. And at 850, the processof the flowchart 800 ends with the results being made available to theuser.

Among the many advantages, the embodiments described herein provide fora reduction in test time for transmitter/receiver systems by determiningmeasured values for multiple properties or parameters as varied for thepackets of a single transmitted packet train or wave train. Testing timeis reduced by measuring one or more packet properties, e.g. outputpower, EVM, and spectral mask, as the properties are varied in valuewithin one single packet train transmission. Furthermore, multiplepacket properties may be measured in a single packet train transmissionwherein the packets are transmitted at different data rates. Many modemdata packet signal receivers are capable of receiving at multiple datarates (e.g. have multiple modems) and may have all data rates tested bya single packet train transmission and reception. Thus, by employing themethods as described herein with more modern test equipment, e.g. a VSAand/or VSG, modern production measurement equipment may be configuredand used to provide a single variable multi-packet wave train ortransmission to reduce the testing time for both complex high frequencytransmitters and receivers.

The above detailed description of the invention and the examplesdescribed therein have been presented for the purposes of illustrationand description only and not by limitation. For example, the operationsdescribed may be done in any suitable manner. The method steps may bedone in any suitable order still providing the described operations andresults. It is therefore contemplated that the present invention coverany and all modifications, variations or equivalents that fall withinthe spirit and scope of the basic underlying principles disclosed aboveand claimed herein.

1-14. (canceled)
 15. A method for testing a data signal receiversupporting multiple data rates, comprising: receiving by the data signalreceiver a plurality of data signals, wherein at least first and secondones of a portion of the plurality of data signals have first and secondones respectively of at least two receiver-supported data rates;determining from the received portion a total number of correctlyreceived data signals; and comparing the total number of correctlyreceived data signals to a predetermined number.
 16. The methodaccording to claim 15, wherein said receiving includes receiving atleast first and second data signals of the received portion of theplurality of data signals at first and second substantially equal powerlevels respectively.
 17. The method according to claim 15, wherein saidreceiving includes receiving at least first and second data signals ofthe received portion of the plurality of data signals at first andsecond different power levels at first and second differentreceiver-supported data rates, respectively.